Hydraulic die shaping press having flexible forming pad



April 1, 1947. w BRlDGENS 2,418,393

I HYDRAULIC DIE SHAPING PRESS HAVING FLEXIBLE FORMING PAD Filed 001;. 12, 1944 Altorney Patented Apr. 1, 1947 HYDRAULIC DIE SHAPING PRESS HAVING FLEXIBLE FORDIING PAD Walter Roy Bridgens, Bramhope, Leeds, England Application October 12, 1944, Serial No. 558,308 In Great Britain July 8, 1943 2 Claims. (01. 11s 4) This invention has reference to hydraulic presses and more particularly to such presses having a rubber or like flexible operating pad which is pressed by hydraulic pressure against an article or blank to be shaped on or in a former carried on a member complementary to the operati g pad.

In presses of this kind it is usual to mount the flexible operating pad across the opening of a hollow member constituting part of the casing of the press, more or less bell-shaped, to which the liquid is admitted and which, under pressure, forces down the operating pad against the work, its flexibility allowing it to flow about the article or blank to be shaped and thus force it to take the shape of the former. This arrangement is quite satisfactory for many purposes, but is not so successful when the article or blank to be shaped is made of metal, as the operating pad, which is attached at its edges to the casing of the press, is, when under the pressure of the liquid above it, not only pressed down, but is also under tension from edge to edge, and any out in the operating pad may cause severe damage as it is well known that even a slight cut in rubber in tension is much more serious than a similar cut in rubber under compression; in fact it is often diflicult to cut rubber under compression or even to penetrate it.

This invention has for its object to provide a flexible-operating pad hydraulic press which can be used for pressing metal and other hard substances without risk of damage to the operating pad and with better results in the pressings made, than has so far been possible.

According to this invention in hydraulic press of the kind referred to the flexible operating pad is connected to the casing of the press by a flexible web or annulus of thin material, herein referred to as a diaphragm, as compared with the thickness of the operating pad, which will give when pressure is applied to force the operating pad down, thus relieving the operating pad of tension, and allowing it to do its work entirely under compression.

The invention is more particularly set forth with reference to the accompanying drawings in which a press according to this invention is shown, without any of the liquid pipes or valves which are necessary on the press but do not form part of this invention.

Fig. 1 is a sectional elevation of the press with the operating pad up.

Fig. 2 is a similar view with the operating pad 4 down, and showing an inverted cup-shaped article being pressed.

Fig. 3 is an elevation of the press showing the open position in dotted lines. 7

The press shown in the drawings is one which opens at one side and is known as an oyster press, but the invention is not limited to such a press, as it may be used with a press of any construction in which a flexible operating pad can be used, I

The press, as shown in the drawings, and which may be circular, rectangular or any other desired shape in'plan, comprises a base 4 and a top 5. It is essential that the two parts shall be firmly secured together, or they may in fact be made in one, leaving an opening at one end whereby the articles to. be pressed can be inserted and removed. It will be appreciated that whatever construction is adopted the press must be of great strength to withstand the strains present when itis being used.

The base has a cavity I! in which the moulding operation takes place and which the operating pad 6 enters at the top, a slight clearance being allowed at each side as shown in Fig. 1; when the operating pad is down it fills the cavity I! as shown in Fig. 2 save for the space occupied by an article H3, or articles, being moulded and the formers IE to which the articles are shaped, the shaped article being indicated by a thickened line. The diaphragm 6 is flexible and has a thick middle part which is the operating pad. The edges of this thinner part or diaphragm I are firmly clamped on the underside of the cover 5 by a clamping ring or surround 8, and the lower face of this clamping ring 8 lies on the top of the flange 9 of the bottom part.

As shown in Fig. 3 and as already described this press is made to open oyster fashion and to this end the parts are hinged at H] and the top and bottom parts have co-operating hinge-joint members II which, when the press is closed, are locked by passing a long rod l2 through the aligned openings l3. Conveniently, a press of this kind is opened and closed by a hydraulic cylinder I6 but any other convenient arrangement may be used.

Where the press does not open in this manner it has an opening at one end through which a tray, carrying the articles to be moulded, can be slid, the end of the tray closing the opening at the end.

The underside of the top 5 has a cavity M to which liquid under pressure can be admitted and from which it can be withdrawn, and this is controlled by pipes and valves not shown in the drawings. Nearer to the edges are downward projections l5 around which, as shown in Fig. 1, the diaphragm 1 curves when the operating pad is up. These projections l5 are so made that part of the diaphragm which lies over them is long enough to allow the operating pad to occupy the cavity I'I inthe lower part 4 merely by giving, and it may also be by stretching slightly, but substantially the length of the thin part, from the edge of the thick part to the nip between the top part 5 and the clamping ring 8,'is the same whether the operating pad be up or down.

It will be understood that when the liquid under pressure enters the cavity M, the pressure is exerted and the diaphragm is forced down, the operating pad descending very much as if it were a ram suspended on the diaphragm '1 which gives, and thus wholly relieves the operating pad of tension, and accordingly comes under pressure only, when it engages the article or blank l9 and presses it to the shape of the former [8, none of the pressure being used, as hitherto, in stretching the operating part.

By this means an effective press can be made which is capable of pressing hard substances such as metal without the danger of damage to the operating pad which danger isalways present when the operating pad is in tension.

It is to be understood that while, in the drawings, the operating padis shown as a thick part 6 on a thin part or diaphragm I, that the two are, in efiect, one unit, both parts being bonded together, or if desired, made in one at the time of manufacture.

What I claim as my invention and desire to secure by Letters Patent is:

1. An hydraulic press comprising a top part and a bottom part, said top part having a cavity closed at the bottom by a flexible diaphragm secured at its edges in said top part, said top cavity having inlets and outlets for a pressure liquid, said bottom part having a cavity wherein the pressing operation takes place, and a flexible pad carried by said diaphragm at the underside thereof, said pad being of such size as substantiallyto fill said cavity in said bottom part and to be wholly under compression when operating in said cavity. I

2. An hydraulic press compriisng a top part and a bottom part, said top part having a cavity closed at the bottom by a flexible diaphragm secured at its edges to said top part, said cavity having inlets and outlets for a pressure liquid, said bottom part having a cavity wherein the pressing operation takes place, and a flexible pad carried by said diaphragm at the underside thereof, said pad being of suchsize as substantially to fill said cavity in said bottom part, said top and bottom parts being shaped so that said diaphragm is of substantially the same length across both when up and when down, whereby the diaphragm is never under more than a slight tension and the pad, when filling said cavity in said bottom part, and when under operating pressure, is Wholly under compression.

WALTER ROY BRDDGENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,468,706 Harrison Sept. 25, 1923 2,280,865 Stossel Apr. 28, 1942 2,344,743 Smith Mar. 21, 1944 2,348,921 Pavlecka May 16, 1944, 2,354,005 Flowers July 18, 1944 

